Heat sink assembly

1. Field of the Invention

The present invention relates to a heat sink assembly, and more specifically to a heat sink assembly having a fixing device for readily securing a fan to a heat sink and pressing the heat sink onto a CPU.

2. Related Art

A conventional heat sink assembly for a CPU includes separate parts such as a heat sink, a heat sink clip, a fixing device and a fan. In assembly, the fan is mounted to the heat sink by the fixing device. Then the combined heat sink and fan is secured to a top surface of the CPU by means of the clip engaging with catches on a CPU socket or holes in a printed circuit board. The clip and the fixing device are separate parts which must be installed or removed separately. This is unduly time-consuming and costly.

Furthermore, the fan is frequently secured to the heat sink using a plurality of screws engaging with fins of the heat sink. The screws frequently distort or even damage the fins. Moreover, fins of contemporary heat sinks are often particularly thin, to maximize dissipation of great amounts of heat generated by contemporary CPUs. Thus it is becoming increasingly difficult to adequately secure a fan to a heat sink using screws.

An improved means of securing a fan to a heat sink which overcomes the above problems is desired.

Accordingly, an object of the present invention is to provide a heat sink assembly having a fixing device which readily attaches a fan to a heat sink and presses the heat sink onto a CPU.

Another object of the present invention is to provide a heat sink assembly having a fixing device which is simply in structure and cost-efficient.

To achieve the above-mentioned objects, a heat sink assembly comprises a heat sink, a fan, and a fixing device. The fixing device comprises an engaging portion for pressing the heat sink onto a CPU, and a fixing portion for securing the fan to the heat sink. The engaging portion has a pressing section received in a slot of the heat sink, two spring sections at each side of the pressing section also received in the slot, and two legs depending from opposite ends of the spring sections. An aperture is defined in each leg, for engaging with a corresponding catch of a socket. The fixing portion has a frame, and four clamps in the vicinity of four corners of the frame. Each clamp has a slit, and a pair of barbs at a distal end of the clamp. A pair of integrating flanges depends from opposite sides of the frame, each integrating flange integrally connecting with a corresponding leg of the engaging portion.

Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention together with the attached drawings, in which:

FIG. 1 is an exploded view of a heat sink assembly in accordance with the present invention, for mounting onto a CPU and a socket;

FIG. 2 is a perspective view of a fixing device of the heat sink assembly of FIG. 1; and

FIG. 3 is an assembled view of FIG. 1 .

Referring to FIG. 1, a heat sink assembly in accordance with the present invention comprises a fan 50 , a heat sink 30 , and a fixing device 10 . The fixing device 10 secures the fan 50 to the heat sink 30 , and engages with a socket 20 to press the heat sink 30 onto a CPU 40 .

The heat sink 30 comprises a base 32 , and a plurality of parallel fins 34 extending upwardly from the base 32 . A vertical slot 36 is defined through a middle portion of the fins 34 , and perpendicular to the fins 34 . The socket 20 forms a catch 22 at each of two opposite lateral sides thereof. The fan 50 defines a through hole 52 in the vicinity of each of four corers thereof.

Referring also to FIG. 2, the fixing device 10 is integrally made from a metal sheet. The fixing device 10 comprises an engaging portion 12 for pressing the heat sink 30 onto the CPU 40 , and a fixing portion 14 above the engaging portion 12 for securing the fan 50 to the heat sink 30 .

The engaging portion 12 comprises a pressing section 122 , two spring sections 124 extending upwardly and outwardly from respective opposite sides of the pressing section 122 , and two legs 126 depending from outer ends of the spring sections 124 respectively. A pair of folded flanges 128 is formed at opposite sides of the pressing section 122 and the spring sections 124 , for reinforcing the pressing section 122 and the spring sections 124 and for increasing pressing force applied on the heat sink 30 . An aperture 130 is defined in the vicinity of a distal end of each leg 126 , for engaging with the corresponding catch 22 of the socket 20 .

The fixing portion 14 has a rectangular frame 142 and four clamps 144 respectively extending upwardly from four corners of the frame 142 . A pair of integrating flanges 149 respectively depends from opposite outer lateral edges of the frame 142 . Each integrating flange 149 further extends downwardly at a middle portion thereof, thereby integrally connecting with the corresponding leg 126 of the engaging portion 12 . A pair of plates 146 respectively depends from middle portions of opposite inner longitudinal edges of the frame 142 . The clamps 144 respectively correspond to the four through holes 52 of the fan 50 . A slit 148 is defined through a middle portion of each clamp 144 . Each slit 148 effectively divides the clamp 144 into two halves, thereby providing deformation space for the clamp 144 . A pair of barbs 150 is formed at a distal end of each clamp 144 .

Referring also to FIG. 3, in assembly, the clamps 144 of the fixing device 10 are extended through the corresponding through holes 52 of the fan 50 . The barbs 150 engage with an upper surface of the fan 50 at the through holes 52 , thereby securing the fan 30 to an upper surface of the frame 142 . The CPU 40 is mounted to the socket 20 . The heat sink 30 is placed on the CPU 40 . The combined fixing device 10 and fan 50 is placed on the heat sink 30 , with the pressing section 122 and the spring portions 124 of the fixing device 10 accommodated in the slot 36 of the heat sink 30 . The fan 50 is pressed downwardly, thereby forcing the engaging portion 12 at the apertures 130 to engage with the catches 22 of the socket 20 . Thus, the pressing section 122 firmly presses the heat sink 30 against a top surface of the CPU 40 . The plates 146 of the fixing device 10 respectively abut against opposite outmost ends of the fins 34 of heat sink 30 , thus preventing lateral movement of the heat sink 30 relative to the CPU 40 .

The fixing device 10 of the present invention integrally comprises the engaging portion 12 and the fixing portion 14 . The engaging portion 12 presses the heat sink 30 against the CPU 40 , and the fixing portion 14 simultaneously secures the fan 50 to the heat sink 30 . Thus the fixing device 10 is easily made at low cost, yet performs the said simultaneous functions of pressing and securing.

It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present example and embodiment are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.